Levan fructotransferase from Arthrobacter oxydans J17-21 catalyzes the formation of the di-D-fructose dianhydride IV from levan

Abstract

A new levan fructotransferase (LFTase) isolated from Arthrobacter oxydans J17-21 was characterized for the production of difructose dianhydride IV (DFA IV). LFTase was purified to apparent homogeneity by Q-Sepharose ion exchange chromatography, Mono-Q HR 5/5 column chromatography, and gel permeation chromatography. The enzyme had an apparent molecular mass of 54000 Da. The optimum pH for the enzyme-catalyzed reaction was pH 6.5, and the optimum temperature was observed at 45 °C. The LFTase was activated by the presence of CaCl2 and EDTA-2Na but inhibited strongly by MnCl2 and CuSO4 at 1 mM and completely by FeSO4 and Ag2SO4 at 1 mM. A bacterial levan from Zymomonas mobilis was incubated with an LFTase; final conversion yield from the levan to DFA IV was 35%. Neither inulin, levanbiose, sucrose, dextran, nor starch was hydrolyzed by LFTase. DFA IV was very stable at acidic pH and high temperature, thus indicating that DFA IV may be suitable for the food industry and related areas.